Expanded Rails 5 Test Case for ActiveSupport::Concern::UnreachableIncludedBlock

circular_class.rb

class Fixtures::Concern::CircularClass
  A = "a"

  include Fixtures::Concern::CircularConcern
end

circular_concern.rb

module Fixtures::Concern::CircularConcern
  extend ActiveSupport::Concern

  B = Fixtures::Concern::CircularClass::A

  included do
  end
end

concern_test.rb

require 'abstract_unit'
require 'active_support/concern'

class ConcernTest < ActiveSupport::TestCase

  # ...
  
  module ::Fixtures
    extend ActiveSupport::Autoload

    module Concern
      extend ActiveSupport::Autoload
    end
  end

  test "test_raise_when_included_block_unreachable" do
    module ::Fixtures::Concern
      eager_autoload do
        # Autoload CircularConcern before CircularClass
        autoload :CircularConcern, "fixtures/concern/circular_concern"
        autoload :CircularClass, "fixtures/concern/circular_class"
      end
    end

    assert_raises(ActiveSupport::Concern::UnreachableIncludedBlock) do
      ::Fixtures::Concern.eager_load!
    end
  end
end